Survey Examples

Surveys at two golf courses in Dublin, Ohio, tested the effectiveness of EMI for golf-course applications. At the Golf Course of Dublin (GCD), measurements were made over a practice green constructed using the California method. At the Muirfield Village Golf Course (MVGC), measurements were made at the seventeenth hole, over both the USGA-method green and the professional tee.

At each site, the H/P-1 was pulled in a sled at walking speed along east-west traverses. Measurements were at 1/8-second intervals, which yielded about eight measurements per meter along the survey traverse. Closely spaced measurements are essential for mapping golf-course features that might include an irregular boundary between sand layers and native soil. The survey traverses were visually controlled according to markers at each end of the traverse, and the nominal spacing between traverses was 1 m.

Figure 21.4 presents profiles of apparent conductivity from traverse 10 N, through the center of the GCD California-method practice green. The apparent conductivities for both HCP and PRP are around 55 mS/m at the ends of the traverse, indicating that native soil of about this conductivity extends to the surface. Over an apparent transition zone of about 2 m (between eastings 1 to 3 and 20 to 18), the PRP apparent conductivity decreases from native-soil levels to about 30 mS/m. This decrease is consistent with a thickening to about 0.3 m of a subturf layer of sand, with conductivity of about 10 mS/m. A decrease in PRP apparent conductivity of a few mS/m at easting 11, and perhaps at easting 6, may indicate thickening of the sand or other coarse material coincident with drainage structures.

Figure 21.5 and Figure 21.6 are contour maps of the H/P-1 apparent conductivities from the traverses on the GCD green. The PRP contours of Figure 21.5 reveal a rectangular area of apparent conductivities below 34 mS/m, figure 21.4 Traverse 10 N at the Golf Course of enclosed by apparent conductivities in the 40s Dublin (GCD). and 50s of mS/m. In this and subsequent maps,